Explosive actuated tool



July 17, 1962 H. BEHREND 4 EXPLOSIVE ACTUATED TOOL Filed March 51, 1961 Fig./

Fig.3

I9 20 I8 20 l7 I6 20 I3 20 3 I United States Patent 3,044,071 EXPLQSIVE ACTUATED, TOOL Herbert Behrend, Kehler Strasse 6, Dusseldorf- Unterrath, Germany Filed Mar. 31, 1961, Ser. No. 99,896 Claims priority, application Germany Apr. 6, 1960 6 Claims. (Cl. 1-44.5)

This invention relates to improvements in explosive tools for the insertion of bolts into masonry and the like.

Explosive tools or hammers for driving'bolts into masonry and other hard substances have been proposed in which a piston of a plurality of diameters mounted in a barrel is actuated by an explosive charge in a cartridge to drive the bolt into the masonry or the like.

The object of the present invention is to so construct the end of the barrel in contact with the masonry or the like that the movement of the piston does not cause damage to the tool and does not drive the bolt too far into the masonry or the like.

The tool is prevented from being over-stressed by arresting the movement of the piston against a guide for the smaller diameter of the piston which is in contact with and a contact member on the forward end of .the guide to engage the masonry.

The invention will be described with'reierence to the accompanying drawings which show two arrangements of the tool.

FIG. 1 is a longitudinal section of one form of tool;

FIG. 2 is a longitudinal section of a further form, and

FIG. 3 is a longitudinal section similar to FIG. 1 showing the piston at the end of the operating stroke.

The tool comprises a breech 1 having a trigger hammer 2 and a barrel 3 affixedto the breech, preferably by screwing. A cartridge 4 is inserted into a bore i the barrel.

The barrel 3 is formed with an internal cylindrical chamber 13 having a counterbore to receive a cylindrical end 12 of a piston unit in contact with the cartridge 4. The piston 'unit is formed with a cylindrical portion 14 of a diameter to be a sliding fit in the chamber 13 and having a piston ring 15, with the forward end of the piston being again reduced in diameter to act as a hammer for a bolt 7. 'The forward end of the piston slides in a guide sleeve 6 extending outwardly beyond the muzzle end of the barrel 3.

A ring 9"is screwed into the end of the barrel 13 and is formed with a here through which the cylindrical guide sleeve passes and which forms a bearing therefor.

The end of the guide sleeve 6 in the chamber 3 is provided with a head 8 which is also a sliding fit in the chamher, the forward movement of the guide 6 being limited by the front face of the head engaging the rear face of the ring 9.

A resilient bufier ring 10 of rubber or like material is secured around the forward end of the guide 6 and contacts the forward face of the head 9 and a spring may 3,044,071 Patented July 17, 1962 be provided between the end of the hammer and the bolt to be driven into the masonry or the like.

Passages 16 are provided through the cylindrical portion 14 of the piston and a further passage or passages 17 through the head 8 of the guide sleeve 6 communieating with a longitudinal and radial passageway or passageways 19 in the ring 9 for the passage of exhaust gases to atmosphere as shown by the arrows 20, FIG. 3.

In operation the butter ring 10 on the muzzle end of the barrel 3 is placed in contact with the masonry or the like into which the bolt 7 is to be tired (FIG. 1) the bolt 7 having been inserted into the bore in the guide sleeve 6. The trigger hammer 2 is released to fire the cartridge 4, the products of combustion from which act on the end 12 of the piston to force the piston unit forward in the chamber 13, any air therein being expelled through the passageways 17, :19 to atmosphere. The forward movement of the piston unit is arrested by the head 8 of the guide sleeve 6. The products of combustion escape as shown by the arrows 20 (FIG. 3).

The rapid movement of the piston unit imparts a hammer blow to the bolt 7 and its movement is then retarded by contact between the portion 14 engaging the head 8 of the guide 6 which imparts the impact through the guide and buiier ring 10 to the masonry or the like, thereby minimising wear and tear on the tool.

The buffer ring 10 may be secured to the guide 6 by a spring ring (FIG. 2) and may be reinforced by a metal Washer or' the like moulded into the ring 10. The ring 10' may extend in front of the end of the guide sleeve 6 to prevent damage to the outer end of the bore therein.

A resilient guide may be provided on the bolt 7 to maintain the bolt centrally of the bore in the guide sleeve 6.

I claim:

1. An explosively actuated driving tool comprising a barrel having a cartridge receiving chamber at one end, a guide bearing fixed to said barrel at the other end, a piston member slidably mounted in said barrel, said piston member having a diametrically reduced front portion, a diametrically reduced rear portion and an intermediate piston head, a combustion bore disposed forwardly of said cartridge receiving chamber and communicating therewith, said combustion bore being adapted to receive the inner end of said diametrically reduced rear portion, a guide sleeve received in said other end of said barrel and slidable axially of said piston member, the outer end of said guide sleeve being received in said guide bearing and projecting from said barrel, buffer means fixed to said outer end of said guide sleeve and adapted to engage the front of said barrel, said front portionof said piston member engaging the inner end of said guide sleeve, said guide sleeve and its buffer means being at least as long as said 'front portion of said piston member.

2. An explosively actuated driving tool according to claim-1 wherein said guide sleeve has an annular head portion at said inner end, said annular head portion engaging the inner wall of said barrel and forming an abut- V merit for said piston head portion.

3. An explosively actuated driving tool according to claim 2 wherein said annularhead portion of said guide sleeve and said piston head portion have an axial passage- 3 way and said guide hearing has an axial and a radial passage-way, said passage-ways providing a combined passage-way for the combustion gases from said expansion chamber to the outside atmosphere.

4. An explosively actuated driving tool according to claim 1 wherein the end of said diametrically reduced rear portion of said piston member is an enlarged cylindrical portion having a close sliding fit with said combustion bore.

5. An explosively actuated tool according to claim 1 wherein said one end of said barrel and said intermediate piston head portion define an expansion chamber for the combustion gases.

6. An explosively actuated driving tool according to claim 5 wherein said axial passage-ways in said annular head portion and in said piston head portion communicate when said head portions are in engagement with each other.

References Cited in the file of this patent UNITED STATES PATENTS France May 27, 1953 

